Duplex telegraph system



April 13 ,192s. 1,580,192

J. M. FELL DUPLEX TELEGRAPH SYSTEM.

Filed Sept. 20, 1924 2 Sheets-Sh eet 1 Z1 M I j IN VEN TOR JJZFeM ATTORNEY April 13-, 1926. 1,580,192

.J. M. FELL DUPLEX TELEGRAPH SYSTEM FiledSept. 20, 1924 z'sneets-sheet 2 7b sabmztiaw circuit army 5 ormzeway repmzen IN VEN TOR WTORNE Y Patented Apr. 13, 1926.

. UNITED STATES PA EN F I JOHN 1V1. FELL, 0F HACKENSAGK, NEW '3 ERSEY, ASSIGNOR TO .AJVIERIGAN TELEPHONE AND TELEGRAPH. COMPANY, A CORPORATION OF NEW YORK.:

nuPLEx TELEGRAPH-SYSTEM.

Application filed September 20, 1924. Serial No. 738,911.

To all whom it may concern:

'Be it known that I, J o- N zen of the United States, residing at Hackensack, in the county of Bergen and State of New Jersey, have invented certain Im-.

provements in Duplex Telegraph Systems,

. of which the following is a specification.

This invention relates to duplex'systems, andparticularly, to arrangements for adding local telegraph loop circuits or branch lines to telegraph repeaters used for through repeating in duplex telegraph systems. The arrangements of the invention may be utilized for full duplex operation, i. e., trans-'v mission both ways simultaneously, and for half-duplex operation, i.-e.,t'ransmiss'ion one way atatime There is a limit to the length of telegraph lines that can be efficientlyoperated between'any two stations. The more important of the limitations are the general electrical properties of the line and the quality of the service that 'mustbe maintained. When it is desired to operate a telegraph circuit of greater length than the normal'operating limit, two or more lines of efficiently operable lengthare joined through telegraph repeaters,which receive the signals from one line and re-tran'smit them with new energy to the next line.;

The repeaters are often located at points where local telegraph stations must be operated in connection with a through line. One of the features of this invention is to provide a simpler, more economical type of through repeater for installation at the repeater stations,'and to provide a limited number of comparatively inexpensive units,

each of which may be connected to any repeater for the purpose of operating local telegraph loops or branch lines in connection with the through circuit. Other features and advantages of the'invention will appear more fully from the detailed description hereinafter given. 7

In outlining the nvention above andhereinafter describing it, the arrangements for a difierential type of duplex repeater for grounded lines have been referred to. v. Embodiments of the invention are obtainable for other types or" repeaters for grounded lines, for metallic telegraph repeaters and i L'FELL, a 01a for mechanical type repeaters of the carrier telegraph system. V j

The invention will be more fully understood; when read in connection with, the

accompanying drawing, in which Fig. 1 is a circuit diagram of a through repeater,

Fig. 2 is a circuitdiagram of anarrangement for operating a loop at the repeater station in a halfduplex system, Fig. 3" is a circuit diagram of an arrangementfor operating loops at the repeater stationin full duplex system, and Fig. 4 is a circuit diagram of a modification of the arrangements of Fig. 2, suitable for half duplex operation.

Referring to Fig. 1, lines L, and L and the balancing artificial lines A1 and A1 are .associated; with a through repeater, the

essential parts of which are diagrammatie cally represented. The armature of relay A moves between the marking' and spacing contacts M and S of said relay, thereby alternately connecting the oppositely poled batteries B and B respectively, and the armature of relay'B moves between its contacts so as to alternately connect the oppositely poled batteries B and B v For signals originating in line L relay A responds, andrepeats the signal impulses into the circuit extending to the apex of relay B. At this point the impulses divide between line L and the artificialline A1 in the usual way,having no effect upon relay B. The impulses pasing over;line L operr ate the receiving relay at thedistant end of the line. A branch circuit extends from the armaturejofirelay A through resistance 13- and the polarized sounder N ,A small portion'o'f'the signal impulses flows inthis branch circuit o eratln sounder N to reproduce the signals for monitoringpurposes.

Similarly, the'signals originating in line operate relay B, which repeats them into line L and sounder N I Figure 2 diagrammatically represents an arrangement for'operating a loop atthe repeater stations when the duplex system is used for half duplex operation, "i. e., for transmission one way at a time. In this arrangement jacks J and J 2 are added to the through' repeater and plugs P and P areinserted in jacks J and J respectively,

for the purpose of connecting equipment for operating a loop circuit. The tip conductor of plug P engages the long spring of ack J thereby connecting the armature of relay A to the marking contact of relay G, and the sleeve of plug P, engages the shell of ja'ckwJ thereby connecting the iapexa-ot the windings a and Z) of relay B to theiarmature of relay G. The tip conductor and the sleeve of plug P engage, respectively, the long spring and the shell of jack thereby connecting the armature of relay B with the marking contact M of relay H and the apex of the windings a and b of relay "A with the armature of relay H.

The-circuit from the armature of relayA thus passesithrough the armature of relay G before it reaches the apex of'relay '13. There is also a circuit from the tip. side of plug P through conductor t and. the c windings of .relays E, and F to ground. Hence, a portion of the signal impulses'flows through this branch circuit and operates relays E andF. ,Relay E repeats the signals into the loop circuit, which includes a monitoring sounder S,- and. may. extend. to a sub-station to operate sounder 8,. :Relay F causes relays I, G; and, H. tobe. locked in their closed positions by current from the batteryfB when the otherwindingsof these relays areopened by the contact of relay E, as explained v.in applicants copending application entitled Duplex telegraphy, filed. NOVGIIlbGIzlG, 1921, Serial Number 515,645.

The operation ofthe arrangementsof Fig. 2 is as follows: Signals originating .in line L are repeated by relay A through the closed contact of relay 7G. to line: L and through: theribranch circuitof conductor 25 to the owindingsor" relaysE andF. Relay E repeats the signals into the connected circuit .whilerelay IF ipreventsrepetition of these signals back to the through line Similarly, signalsoriginating in lineiL are repeated by relay B throughthe closed contact of relay H: toline L,,.and through the branch circuit-from; plug]? and conductor 'wto the a windings of relays C and D. Relay C repeats thesignals into the loop circuit and relayID causes relaysiI, G and H to ,be locked. 7

By operating keys K, or K, signals originating in the loop circuit operate. relays I, G and H. .Relay G repeatsithese signals into line L and relayvH" into L Inarkingcurrentsfor; relays GR and li-bcing obtained; from batteries LB, and B, through the marking contacts of relays 1A and B, respec-tively,-. and the spacing currents from batteries B and B respectively. -,The functionlotrelayi I which is toxinsure-the transmission of a break signal: from the loop circuit ,is fully explained in the copending application mentioned heretofore, filed No- Vember 16, 1921, Serial Number 515,643. The local circuit is of the type known as the three or more way and can be operatedin series with similar": circuits of other duplex repeaters, and, thus, other lines may be connected to the through line at any repeater-station- When: the SySiEQIHLlSJOPBIZLtQC l full duplex, i. e., simultaneous messages in both directions, loopsmay be added at a through repeater as diagrammatically represented in Figure "The local loop circuits are connected to the through repeater by inserting plugs P andjP in jacks andal respectively.

Incoming signals from the westerly line L are repeatednby relay A through the marking contact of relay G to line L,, current also flowing through the branch circuit which includes winding 0 of relay C. .Relay C repeats the signals'into the loop circuit,whi'ch includes the sounder S at the repeater station and sounderfS at the sub-station. Similarly, signals from the easterly line lL operatezrelay B andare repeated through the marking contact M of relay H to lineL current also flowing through winding 0 of relay D. .RelayiD repeats these signals into theploop, circuit, which-includes sounder S at the repeater station and sounder. 8,, .at the sub-station.

, It is possible with-,the arrangementsof Fig. 8 to'transmit messages to. either or both linesL or. L, as it may. be required. Then switch Q is opened the sub station may transmit to both lines ibyoperating key K, or key K ,..which control the pole changingrelays G and H, or the sub-station may transmitto lineL only,.by closing switch Q :and operating key K whichv then controls pole, changingcrelay. Gonly, or to. line L only, by. operating key K with-switch Q. closed. Eor such transmission-of messages from the substation, batteries *B, i and 113 supply theumarking currents,.and batteries B and, B supply: the spacing cur rents.

Figures-is a modification of the arrange ments of Figure 2, in-which two relays, C andD, are used in'place of-the four relays G,D,'E-and E of Eigure 2. This arrangement --,is suitable for half duplex operation, i. e, transmission one way "at. a time.

Marking and spacing signals in either line L, or L, will be repeated in-exactly the same manner as heretofore described. The relays represented as C and D have two windings each. iTheawfinding of these relays are included ,in.a circuit .with resistance r 'itrom the tip sideofrplug P, to the tip side otplug P The l) windings of these relays are in Cluded in the local circuit with battery 18,,

and resistance r A small-current through i this latter circuit tends to keep the relay arinatures on their spacing contacts. When the armatures of relays A and B are against the marking contacts battery B will assist battery B in sending a current through the a. windings of relays C and D, and consequently, the armatures are held on their marking contacts M. \Vhen the. armature of either relay A 'or relay B is moved, to its spacing contact S, no current flows through the a windings of relays C and D,'since the batteries at opposite ends of the circuit which includes their windings are then alike in potential and polarity. The ai'inatures oi relays C and D are therefore moved to their spacing contacts. Relay Ocontrols the loop circuit, including sounder S and possibly a sounder at the sub-station, and relay D controls the locking feature of relays I, G and H, as heretofore described. It is obvious also that if the armatures of'i'elays A and B are on their spacing contacts at the same time, the direction of the current through relays C and D is reversed and the arniatures of these relays are moved to their I spacing positions.

For transmission of signals from the substation to lines L and L key'K or a key at sub-station is. operated. Upon opening the key no current flows from the battery B through the a windings of relays I, G and H and the armatures of said relays move to the spacing contacts. Battery B energizes line L for a spacing signal, and battery B energizes line L, for a like signal. Upon clos ing the key current again flows through the a windings of relays I, G and H, and the arniatures of said relays move to the marking contacts. Battery B supplies the energy necessary to transmit the marking signal to line. L and battery B supplies the energy for transmission of the marking signal to line L While the invention has been disclosed in certain specific arrangements which are deemed'desirable, it is to be understood that it is capable of embodiment in many and widely varied forms without departing from the spirit of the invention as defined in the appended claims.

IV hat is claimed is: V 1. In a duplex telegraph system, a through repeater in which a polarized pole changing relay is associated with thefirst line, and a polarized 'pole changing relay is associated with the second line, each repeating signals to the other line, means for connecting aloop' circuit to said through repeater, a repeating relay for repeating signals in said linesto said loop circuit, a control relay operated simultaneously with said repeating relay actuating the means to prevent the retransmission of signals to said lines, and means tor transmitting signals'fromsaid loop circuit to said lines.

2. In aduplex telegraph system, a through repeater in which a polarized pole changing relay is associated with the first line, a polarized pole changing relay isassociated with the second line,-ineans for connecting a local loop circuit to said through repeater, a repeating relay for retraiismitting signals in repeater for repeating signals in a first line to a second line, or vice versa, asounder for monitoring signals in said first line, a sounder tor monitoring signals in said second line,

a polarized pole changing relay associated with said'second line, plugs and jacks to connect a loopcircuit to said through repeater, as sub-station associated with said loop circuit, said sub-station having a sounder and a key to receive signals from and to transmit signalsto said'lines, repeating relays actuated simultaneously by saidpolarized pole changing relays, each of'said r peating relays retraiismittingv signals in each of said first and second lines, respectively to said sub st'ation; two polarized relays operated simultaneously and associated with said plugs and jacks arranged to connect a loop first and sec-ondlines, said polarized relays being locked when signals are being received at said sub-station fromsaid lines, and unlocked when signals are being transmitted to said lines from said sub-station, relays actuated simultaneously withsaid repeating relays to regulate the locking element of said polarized relays.

In testimony whereof, I have signed my name to this specification this 16th day of September, 1924.

' JOHN M. FELL. 

